(a) A person is not guilty of an offense unless his liability is based on conduct which includes a voluntary act.

(b) A "voluntary act" is:

(1) a bodily movement performed while conscious as a result of effort or determination; or

(2) an omission to perform an act of which the actor is physically capable.

(c) Possession is a voluntary act if the possessor knowingly procures or receives the thing possessed, or having acquired control of it was aware of his control for a sufficient time to have enabled him to dispose of it or terminate his control.

(d) A person is not guilty of an offense based solely upon an omission to perform an act unless the law defining the offense provides expressly, or a duty to perform the omitted act is otherwise imposed by law.